Jack announced in early June that had been diagnosed with MS. "He knew something was wrong for a while," a source told Us of the former Osbournes star. "Everyone is sad, but he is being strong about it."

Sharon and Ozzy Osbourne's son lashed out at NBC earlier this month claiming he was fired from an upcoming series, Stars Earn Stripes, following his diagnosis.

"NBC said they didn't fire me over my diagnosis? Bull-F--k----S--t," Jack tweeted, linking to a TMZ report that included a statement from NBC Chairman Bob Greenblatt to the contrary. "I took part in a 16 hour challenge over 30 miles with a 40 pound ruck [sack] on my back in January. I had MS then," says Jack, who was set to compete on the NBC series that features celebrities competing in military-style challenges. "Don't tell me [what] physically demanding is."

Sharon, 59, supported her son by protesting the network and quitting her job as a judge on America's Got Talent. "I just can't be fake," Sharon told the New York Post. "It's discrimination, and it was badly handled."